The present invention relates to electrical components for making electrical contact with another component and electrical devices for conducting electrical current which include at least one of the electrical components. The electrical contact components and devices described herein, in addition to being well suited for low energy electronic/electrical signal level circuitry typified by contemporary digital and analog signal processing practices, are also particularly well suited to high power applications which require high contact power ratings and higher reliability which may rely on high bulk electrical and thermal conductivity and high surface densities of the fiber contact points in the contacts and may, for example, be used in power switching and power commutation applications. Typical of the type of machines which may use electrical contacts and devices are electrostatographic printing machines.
In electrostatographic printing apparatus commonly used today a photoconductive insulating member is typically charged to a uniform potential and thereafter exposed to a light image of an original document to be reproduced. The exposure discharges the photoconductive insulating surface in exposed or background areas and creates an electrostatic latent image on the member which corresponds to the image contained within the original document. Alternatively, a light beam may be modulated and used to selectively discharge portions of the charged photoconductive surface to record the desired information thereon. Typically, such a system employs a laser beam. Subsequently, the electrostatic latent image on the photoconductive insulating surface is made visible by developing the image with developer powder referred to in the art as toner. Most development systems employ developer which comprises both charged carrier particles and charged toner particles which triboelectrically adhere to the carrier particles. During development the toner particles are attracted from the carrier particles by the charged pattern of the image areas of the photoconductive insulating area to form a powder image on the photoconductive area. This toner image may be subsequently transferred to a support surface such as copy paper to which it may be permanently affixed by heating or by the application of pressure, to form the desired copy.
In commercial applications of such printing machines it is necessary to distribute power and/or logic signals to various sites within the machines. Traditionally, this has required conventional wires and wiring harnesses in each machine to distribute power and logic signals to the various functional elements in an automated machine. In such distribution systems, it is necessary to provide electrical connectors between the wires and components. In addition, it is necessary to provide sensors and switches, for example, to sense the location of copy sheets, documents, etc. Similarly, other electrical devices such as interlocks, and the like are provided to enable or disable a function. These electrical devices are usually low power operating at electronic signal potentials up to 5 volts and at currents in the milliamp regime. Further, many commercial applications employ electrical contact components and related devices that require use in higher power applications employing currents in the regime of 1-100 amps and voltages greater than 5 volts. The present invention is not limited to signal level currents or low potential applications, and includes applications in much higher power regimes requiring greater current carrying capacity which is enabled by the lower electrical contact resistance than previously achieved.
Most currently available devices performing both high level and low level contact functions have traditionally relied on metal to metal contact to complete the associated circuitry. While effective in many applications, these conventional devices nevertheless suffer from several difficulties in that metal contacts may be degraded over time by the formation of insulating films due to oxidation of the metal and those insulating films on the metal may not be capable of being pierced by the mechanical contact forces or by the low energy electrical power present in the circuit. Furthermore, these contacts are susceptible to contamination by dust and other debris in a machine environment such as toner particles, which are generally airborne within the machine and may collect and deposit on one or more of the contact surfaces, causing failure of the contact.